This is a colloquial answer which can't be traced to any single person. Back in the peasant days, people would use thatch as roofing. When it rained very hard, the farm animals (cat and dogs, not cows and horses) would take refuge in the rafters (think of sod houses and other structures that might be partially recessed in the ground for heat retention) Sometimes it would be so wet that the pets would lose their footing and fall into the room during the rainstorms.
its raining cats and dogs
It is a saying for it is POURING outside. Just like saying "it's raining cats and dogs"
"It's raining cats and dogs" is an idiom.
The phrase "it's raining cats and dogs!" is hyperbole.
Raining cats and dogs mean that it's raining very hard
No! 'its raining cats and dogs' is an Idiom.
There is an expression - "raining cats and dogs". This does not mean that cats and/or dogs are literally falling from the sky, it simply means that it is raining very hard.
under what headword would you find the idiom raining cats and dogs?
Its raining cats and dogs!
No, the phrase "raining cats and dogs" is an idiom that means raining heavily. It has never happened literally.
It is raining heavily
In olden times people threw rubbish into the street. In amongst the rubbish would be cats and dogs which would be washed along the street during heavy rain. Hence raining cats and dogs. Of course, they are not literally raining from above!